1. Field of the Invention
The present invention relates to drywall finish trim devices typically utilized in finishing a drywall installation at a corner or terminus.
2. Description of the Prior Art
Drywall, sometimes also referred to as wallboard, is a staple in the construction industry as an economical alternative to plaster for forming the interior walls and ceilings of rooms in residential, commercial, and industrial buildings. The materials used in drywall construction include gypsum board, plywood, fibre-and-pulp boards, and asbestos-cement boards. The large, rigid sheets are fastened directly to the frame of a building with nails, screws, or adhesives, or are mounted on furring (strips of wood nailed over the studs, joists, rafters, or masonry, which allow free circulation of air behind the interior wall). A significant advantage afforded by drywall construction is that it allows a builder to avoid delays because the interior walls do not have to dry before other work can be started or to obtain specific finishes. Wallboard is manufactured in both finished and unfinished forms, and finished wallboards may be faced with vinyl or other materials in a variety of permanent colors and textures so that they do not need to be painted when installed.
When employing drywall in construction, builders can easily cut the panels to any desired shape and size. However, workmen face a challenge in finishing drywall panels at an edge or corner. It is very difficult, if not impossible, to cut the edges of such panels with the precision, straightness, and smoothness that is required to abut the edges of adjoining panels to form a straight corner that will afford an aesthetic finish. Additionally, cutting of the drywall panels exposes the soft, raw cores thereof, thus requiring some sort of covering to afford a finished appearance.
As a result, to protect the drywall panel edges and enhance their aesthetic appearance, several devices and techniques may be employed in an effort to produce a structurally sound corner that will exhibit a smooth and seamless intersection. Devices proposed to achieve this result include drywall tape, trim and corner beads. When conventional drywall tape is used, it is applied to the joints and edges of abutting panels and is covered with wet joint compound that is feathered and smoothed to cover the newly created seams. When the joint compound has dried, the tape and drywall can be sanded, painted, covered, or otherwise finished in whatever manner is desired. A great deal of skill is required, however, to apply and form the joint compound to create a sufficiently straight intersection that will exhibit, when taped and sanded to a finish, no evidence of scuffing and tearing in the tape.
In light of the limitations of drywall tape, trim strips or corner beads are often utilized in effort to produce a seamless and aesthetically pleasing edge trim or intersection at the corners of drywall panels.
Such trim may take many different forms and are typically in the form of an angle corner bead having diverging flanges or may be, for instance, a J strip to cap the edge of a dry wall panel. For the purposes of this invention, the particular configuration is not critical but use in conjunction with numerous different configurations is contemplated. For instance, the trim may be flat or configured with any one of a number of well known configurations, including corner trim with perpendicular flanges, corner trim with a rib formed at the juncture of the flanges defining a bead, flanges angled at 135xc2x0 to one another, those configured with somewhat of a Z shape, those with soft line corners, and those with offsets or other configurations traditionally used in the trade and known to those skilled in the art.
To enhance the finished appearance of finished drywall made with such trim, efforts have been made to provide such trim with an exterior covering of paper or paper-like material to facilitate a finishing strip. It is recognized that by covering a metal core with paper, the paper surface may be covered during the finishing process with a joint compound which is then sanded off and feathered in effort to provide a smooth and continuous surface.
A disadvantage arising from the use of such paper covered trim cores is that, during the sanding process, the workman might sand through such compound and sand into the paper layer. This sanding tends to scuff up the fiber in the paper layer leaving somewhat of a scuffed or abraded surface, oftentimes with frayed fiber ends. This results in a discontinuous and unattractive surface. When finished, as by paint or the like, a somewhat fuzzy and porous appearance may result with the exposed fibers and fiber ends presenting an aesthetically unpleasing finish.
Efforts to solve this problem have led to the development of various different trims and corner beads. One such corner bead available in the market is a corner flange having a hard core covered on the exterior with kraft paper, which is then coated with latex. This product has proven somewhat unsatisfactory in the marketplace. First, the latex coating is oftentimes without uniformity in thickness and is often ineffective to provide protection against penetration and fraying by the roughened surface of a finish tool, such as sandpaper. Frequently, the workman will in certain areas sand through the latex coating, thus raising the fibers from the underlying paper and resulting in a dissatisfactory final appearance. A corner bead of this type is shown in U.S. Pat. No. 5,131,198 to Ritchie.
In recognition of the shortcomings of such surface coated paper covering the core of drywall trim, other efforts have been made to provide a more acceptable paper coating for trim core. Corner beads have been proposed that are constructed of a core covered by a wood fiber kraft paper impregnated with latex. Efforts have been made to impregnate such stock paper to a uniform thickness. A device of this type is shown in U.S. Pat. No. 5,613,335 to Rennich. While suitable for its specifically intended purpose, such a bead suffers a shortcoming in that efforts to penetrate paper stock with latex have proven relatively ineffective to provide satisfactory scuff resistant characteristics throughout the thickness of the paper covering.
Other shortcomings of prior drywall trims covered with paper or paper-like covering become evident when they are subjected to high temperatures above about 100xc2x0 F., as during the storage in storage sheds or in transportation thereof. In such instances, the paper covering will often bubble up on the core or will pull away from the core, particularly in the area of any irregularity in the core surface as in the case of any shoulder or rib formed in such core. This bubbling and separation of the paper covering is often detected only at the construction site after the product has been transported and stored for preparation of the drywall phase of the construction project. Consequently, the onsite workman thus oftentimes reject and discard any strips of such deteriorated trim thus resulting in significant waste.
Consequently, there exists a need for a drywall trim which will resist scuffing. It would also be beneficial if such a trim would resist separation of the cover from the core of the trim to thus minimize waste while enhancing the ultimate aesthetics of the finished product.
The drywall trim device of the present invention is characterized by a metal core covered on at least a portion of the exterior side by a cover bonded thereto. The cover is fabricated by mixing a mixture of fiber with a strengthening compound to cover the fibers with such strengthening compound, and forming the mixture into a strip to form the cover.
The strengthening compound preferably fills in the interstices formed between the network of fibers to thus cooperate with the encapsulation of the fibers to minimize any shrinkage of the covering material relative to the core as a result of high temperatures which might cause dehydration.
The trim may be manufactured by fabricating a metal core which can be formed to any desired configuration as dictated by the end use thereof. Strengthening compounds, such as latex, may be mixed with the fiber material in a beater mixing process typically utilized in the manufacture of paper used for book covers and the like. The fiber and latex mix may be formed in a thin film and multiple films combined together to form a covering strip. The individual films or combined layers thereof may be pressed to the desired thickness and to enhance the smoothness of the surface.
In at least one embodiment, the strengthening compound is mixed with fibers in the manufacturing process and the fibrous film and strengthening compound film constructed such that the interstices between the various fibers is filled with the compound to act as a filler in such interstices.
Other objects and features of the invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings.